First of all, it's great that nobody was injured in this crash. Under normal circumstances, the ol' Gooney Bird can fly quite well on one engine. There are only a couple of circumstances that come to what's left of my mind: they were over gross; the failed engine could not to feather ... or maybe a combination of both. If the cause of this crash was that the failed engine couldn't be feathered, the crew did a really good job of getting it on the ground without creating a smoking hole or rolling it up into a ball. I'm sure that there are other factors that may have come into play, and hopefully, we'll hear more details later.
Cheers,
Grog